Rotary operated snap acting device



July 12, 194-9 w. A. MARTIN 2,476,103

ROTARY OPERATED SNAP ACTING DEVICE Filed Feb. 18, 1946 IN V EN TOR.

Patented July 12, 1949 UNITED STATES PTENT OFFICE ROTARY OPERATED SNAP ACTING DEVICE Wilbert A. Martin, Freeport, Ill., assignor to First Industrial Corporation, Wilmington, Del., a corporation of Delaware Application February 18, 1946, Serial No. 648,343

be formed in any suitable manner to receive a stiff wire or other rotatable member, in this case being provided with the drilled hole 3? andthe extensions 38.

By a precision type switch, I refer here to the A snap acting spring member generally desigtype illustrated by the Eaton Patent 2,170,748 and nated 39 comprises a tension member which is various modifications of it. made up of a pair of elongated tension elements Among the objects of this invention is the pro- 4| joined by end portions 42 and 43. The latter vision of a precision type switch which is highly end portion carries the movable contact 44 and compact by reason of the facts that: (1) it has also has attached thereto a spring strip or coma built-in operating member which is limitedly pression element 4t which, in the assembled rotative, thereby dispensing with the volume of switch, is normally bowed in longitudinal coman extra actuator; (2) its operating member pression. The terminal member 24 has formed has a substantial amount of overtravel in both integral with it an upstanding or anchor portion rotative directions beyond the contact-changing 41, so-called because the spring strip end 48 position; and (3) it is operable by very light and the knife edge 49 of the elongated actuating forces. Thus, it is particularly adapted for use member 5| are anchored or pivoted on it in in coin operated devices such as juke boxes, pay grooves 52 and 53 respectively. The anchor portelephones, and the like, Where the switch must: tion 4'! serves additionally as an adjustable (by (1) be compact; (2) operate with a certain as bending) means of limiting counterclockwise amount of overtravel; and (3) be operable by a rotation of the actuator 5| around its lower or feather-like force which may be as low as the pivoted end portion. The actuating member 5| weight of a dime (2 grams). The present inhas the tension member end portion 42 pivotally Vention resides in certain novel features of conengaged within its groove 54; and at its upper struction, combination of parts, and arrangement portion it has the operating surface 56 slidably of apparatus, particularly set forth in the claims, engaged with the operating surface or edge El of and is illustrated by the specific embodiment the cam 32. herein shown and described by way of example. The particular embodiment shown illustrates In the drawings: a self-returning type of switch in which the Figure 1 is a side view with the cover removed parts are arranged so they will tend to assume of one embodiment of my invention; the positions shown in Figure 1 where the mov- Figs. 1a and 1b are top and end views, respecable contact 44 abuts the stop 6! formed as an tively, of Figure 1; integral extension of the terminal member 24.

Fig. 2 is a view similar to Figure 1 showing the This is referred to as the normal position of the movable parts in the opposite or current-carryswitch at which the circuit between the terminals ing position; 24 and 26 is broken. Rotation of the cam 32 Fig. 3 is a sectional view of Fig. .2 taken on the by the operating member 31 will cause it to move line 33, and the actuating member 5| arcuately about the Fig. 4 is an exploded perspective view of the pivot edge 49, at the same time liftin t e e d separable parts of the switch. of the tension member. It will be noted that in Referring now more particularly to the figures, Figure 1 the tension member is located just below the switch illustrated has a base plate 2| onto the pivot groove 52. When the tension member which the cover plate 22 is adapted to be mounted is moved upward by the cam, it will pass through by means of the rivet 23. Terminal members 24 a position or axis of maximum stress where the and 26, having apertures 21 for attachment to pivot groove 52 is aligned with the tension memexternal wires (not shown), are mounted on the bar, and from this position it will snap upwardly base plate 2| by single rivets 28 and 29, resDecinto engagement with the stationary contact 533 tively. An operating member 3|, having the which is formed as an integral part of the terhook-like cam member 32 riveted to its inner minal member 26. The parts will then be in the end, is rotatably journaled within the circular positions shown in Fig. 2, terminals 24 and 26 opening 33 formed in the base plate. The operbeing connected through the spring member 39. ating member 3| is restrained against recipro- In order that the parts be self-returning to the cable movement by means of its shoulder por- Figure 1 position they must be so arranged that tion 34 and the C-washer or snap ring 36. The the tension member will never cross over the outer end portion of the operating member may groove 53; it will be noted that, to this end, the

groove 53 is formed somewhat above the groove 52 on the anchor 41. The anchor portion 41 may be suitably bent during assembly of the switch so as to limit the counterclockwise rotation of the actuating member to prevent the tension member from being moved above it.

When the rotative force is released from the bperating member 3| the actuating member 5| will be rotated by energy stored in the spring 39 until the tension member has once more passed through the axis of maximum stress, at which time the contact 44 will be snapped downwardly out of engagement with the stationary contact 62 and the parts will once more assume the normal positions shown in Figur 1.

Reference will now be made to the overtravel which may be built into the switch. Counterclockwise rotation of the cam 32 is limited by abutment with the stop 58 formed in the 'base portion; and clockwise rotation is limited by a similar stop 59. It will be noted that in Figure 1 the normal position of the cam 32 is such that it can be moved clockwise before abutting the stop 59; this represents overtravel or freedom of movement beyond the normal position in the clockwise direction. Similarly, in the counterclockwise direction, the amount of travel beyond the normal position may be determined by the position of the stop 58, which may be set a number of degrees beyond the operating position as desired. With this construction, it is practical to have from 20 to 25 of travel in each direction beyond the normal or Figure 1 position.

The cam 32 is made to operate the actuator 5| in either rotative direction; however, lower operating forces are required when it is moved counterclockwise by reason of the fact that the force is applied farther from the pivot 49. To this end, the stops 58 may be positioned so as to prevent clockwise but permit counterclockwise operative movement from the normal position.

In Figures 1, 2 and 4 the position of the center line or axis of the cam 32 is indicated by a small a? designated 62. It will be noted that in both the operative positions, Figures 1 and 2, the actuating member 5| is intersected by this center line. In other words, the actuating member and cam operating surfaces 56 and 57 are so positioned with respect to the axis of rotation 62 that rotation of the cam 32 causes the cam engaging surface 56 to move toward, and not away from, the axis 62. I have found this preferable since with this arrangement the force tending to return the cam to the normal position increases rather than decreases as the cam is turned.

Although only one embodiment of the device is described and illustrated it will be understood that the invention is not limited thereto but is limited only in accordance with the scope of the appended claims.

I claim:

1. A snap acting device, comprising spaced tension members interconnected at opposite ends, one of said ends being free to move between preselected positions with a snap action, a compression member disposed between said tension members and having an end interconnected with the free end and the opposite end in spaced relation with the other end of the spaced tension members, a bracket disposed between said spaced tension members and pivotally supporting the opposite end of the compression member, a lever disposed between said spaced tension members and supporting said other end of the tension members; said lever having a projection thereon engaging said bracket on the side thereof opposite the pivotal support for the compression member to form a fulcrum, said tension and compression members in the supported position forming a snap spring system having an axis of maximum stress, and cam means engaging said lever at a position spaced from said fulcrum to move said lever a predetermined distance whereby said other end of the tension members moves relative to the pivotally supported end of the compression member through the axis of maximum stress.

2. A snap acting device, comprising spaced first stressed members interconnected at opposite ends, one of said ends being free to move between preselected positions with a snap action, a second stressed member disposed between said first stressed members and having an end interconnected with said free end and the opposite end in spaced relation with the other end of the spaced first stressed members, a bracket disposed between said spaced first stressed members and pivotally supporting the opposite end of the second stressed member, a lever disposed between said spaced first stressed members and supporting said opposite end of the first stressed members; said lever having a projection thereon engaging said bracket on the side thereof opposite the pivotal support for the second'stressed member to form a fulcrum, said first and second stressed members in the supported position forming a snap spring system having an axis of maximum stress, and cam means engaging said lever at a position spaced from said fulcrum to move said lever a predetermined distance whereby said opposite end of the first stressed members moves relative to the pivotally supported end of the second stressed member to move said snap spring through its axis of maximum stress.

3. In a snap action switch, the combination of a base, opposed stops mounted on said base, a bracket mounted on said base and having grooves formed on opposite sides thereof in spaced relation, a snap spring system comprising a compression member and a tension member, one end of each of said tension and compression members being interconnected and free to move' between the opposed stops with a snap action, the opposite end of said compression member being pivotally supported in one of said grooves, and the opposite end of said tension member being in spaced relation with the opposite end of said compression member, a lever supporting the opposite end of said tension member and having a projection pivotally received in said other groove, said lever being shaped so that movement thereof about its pivotal support moves said tension member relative to the pivotal support of said compression member, and means rotatable about an axis engaging said lever to effect movement thereof.

4. In a snap action switch, the combination of a base, a bracket mounted on said base, a snap spring system comprising a compression member and a tension member, one endof each of said tension and compression members being interconnected and free to move between preselected positions with a snap action, the opposite end of said compression member being pivotally supported on one side of said bracket, and the opposite end of said tension member being in spaced relation with the opposite end of said compression member, a lever pivotally mounted on the opposite side ofsaid bracket and shaped to sup port the opposite end of said tension member, said lever being shaped so that movement thereof about its pivotal support moves said opposite end of the tension member relative to the pivotal support of said compression member, and cam means rotatable about an axis and engaging said lever to effect the aforegoing movement.

5. In a snap action switch, the combination of a snap spring system comprising a compression member and a tension member, one end of each of said tension and compression members being interconnected and free to move between preselected positions, means for pivotally supporting the opposite end of said compression memher, the opposite end of said tension member being in spaced relationwith the opposite end of said compression member, a rigid lever for supporting the opposite end of said tension member, means for fulcruming said lever so that movement of said lever moves said opposite end of the tension member relative to the pivotal support of said compression member, and cam means rotatable about an axis and engaging said lever at a position spaced from said fulcruming means to effect the aforegoing movement whereby said free end moves between the preselected positions with a snap action.

6. In a snap spring system, the combination of, a tension member having an end free to move between spaced positions with a snap action and an opposite end portion, a compression member having an end interconnected with said free end and having an opposite end portion in spaced relation with said opposite end portion of the tension member, means forming a fixed mounting for one of said opposite end portions, a lever providing a mounting for the other of said opposite end portions, means forming a pivot for said lever, and a cam engaging said lever to move the opposite end portion supported by said lever through an axis of maximum stress to move said free end between the spaced positions.

WILBER'I' A. MARTIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Elmer Dec. 16, 1941 Kaminky Mar. 11, 1947 Number 

